The project is a neurobiological investigation of the structure of ascending projections of the brainstem tegmentum and tectum. Experimental neuroanatomical studies will employ autoradiography, horseradish peroxidase histochemistry, and fluorescence microscopy techniques. The cells of origin and areas of termination of projects of the brainstem reticular formation to the diencephalon will be determined. Also, studies will examine the origin and termination of projections from the pretectum and superior colliculus to the thalamus. Particular attention will be focussed on the topographical organization of these projections. A variety of techniques and approaches will be used, and the results will be integrated in an attempt toward an overall understanding of the relationship of the brainstem tegmentum and tectum with the forebrain.